Do you compromise with HCBM?

I (31F) have been a SM for almost 5 years to an awesome SK(8). Custody isn’t quite 50/50.. more like 60/40 with DH people the primary. I am an active parent with DH.

I’m curious how bio parents navigate compromising with HCBPs. From what I understand, compromising can look good in a legal sense for judges and what not. But then again, it’s also crucial to uphold boundaries because we all know if you give an inch they will take 23 miles. And we also know that if we want something, they often refuse to compromise (but they always expect it?!)

Our HCBM in back-to-back texts lied about not communicating something and then immediately asked to get SK on an earlier day because HCBM is going out of town on the day she is supposed to have SK.

Just curious your thoughts. I also understand that a lot of this is situational.